Through-Display Interferometric Proximity and Velocity Sensing

Abstract

An optical sensing system includes a transmitter side and a receiver side, and is configured to be positioned below a display of an electronic device. The transmitter side includes a light emitter. The receiver side includes an array of photodiodes. The light emitter of the transmitter side and the array of photodiodes of the receiver side are optically coupled via a waveguide. As a result of this construction, the optical sensing system can be operated as an interferometric optical sensor.

What is claimed is: 
     
         1 . An electronic device comprising:
 an optical sensing system for detecting proximity of an object external to the electronic device, the optical sensing system comprising:
 a light emitter configured to emit light toward the object; 
 a light sensor array comprising at least two light sensors, each configured to receive light reflected from the object; and 
 an optical waveguide optically coupling the light emitter and the light sensor array. 
   
     
     
         2 . The electronic device of  claim 1 , wherein the light emitter comprises a laser. 
     
     
         3 . The electronic device of  claim 2 , wherein the laser is an infrared laser. 
     
     
         4 . The electronic device of  claim 3 , wherein the optical waveguide is formed from silicon. 
     
     
         5 . The electronic device of  claim 4 , wherein the optical waveguide comprises at least one delay loop. 
     
     
         6 . The electronic device of  claim 5 , wherein the optical waveguide comprises a directional coupler optically coupling an input of the delay loop to an output of the light emitter. 
     
     
         7 . The electronic device of  claim 2 , wherein the light sensor array comprises at least one infrared photodiode. 
     
     
         8 . The electronic device of  claim 1 , comprising a display, wherein the optical sensing system is disposed such that the light emitter is configured to emit light through the display. 
     
     
         9 . The electronic device of  claim 8 , wherein the light sensor array is configured to receive light reflected from the object that has passed through the display. 
     
     
         10 . The electronic device of  claim 1 , wherein the optical waveguide comprises a beam splitter. 
     
     
         11 . An electronic device comprising:
 a housing;   a display within the housing; and   an optical sensing system positioned within the housing and behind the display the optical sensing system comprising:
 a laser light emitter configured to emit light through the display toward an object external to the electronic device; 
 a first photodiode and a second photodiode, each configured to receive light reflected from the object that has passed through the display; and 
 an optical waveguide optically coupling the laser light emitter and at least one of the first photodiode and the second photodiode. 
   
     
     
         12 . The electronic device of  claim 11 , wherein the optical waveguide optically couples the laser light emitter to both the first photodiode and the second photodiode. 
     
     
         13 . The electronic device of  claim 11 , wherein the optical sensing system comprises a processor configured to receive output from the first photodiode and the second photodiode and to determine therewith a velocity of and a distance to the object. 
     
     
         14 . The electronic device of  claim 13 , wherein the optical waveguide is defined at least in part within a photonic integrated circuit. 
     
     
         15 . The electronic device of  claim 14 , wherein:
 the optical waveguide is a first optical waveguide optically coupling the laser light emitter to the first photodiode; and   the optical sensing system comprises a second optical waveguide optically coupling the laser light emitter to the second photodiode.   
     
     
         16 . The electronic device of  claim 15 , wherein the first waveguide and the second waveguide are formed from silicon and the laser light emitter is configured to emit infrared light. 
     
     
         17 . The electronic device of  claim 11 , wherein the display is an organic light-emitting diode display. 
     
     
         18 . The electronic device of  claim 11 , wherein the optical waveguide defines an optical path including at least a portion of the display. 
     
     
         19 . An electronic device comprising:
 a housing;   an organic light-emitting diode display within the housing; and   an optical proximity sensing system positioned within the housing and behind the organic light-emitting diode display, the optical sensing system comprising:
 a collimator positioned below the organic light-emitting diode display; 
 an infrared laser below the collimator and configured to emit infrared laser light through the collimator and the organic light-emitting diode display toward an object external to the electronic device; 
 a photodiode to receive light reflected from the object that has passed through the organic light-emitting diode display; and 
 a waveguide optically coupling output from the infrared laser and to the photodiode. 
   
     
     
         20 . The electronic device of  claim 19 , wherein the waveguide comprises at least one delay loop.